Abstract
Positron emission tomography (PET) has been proven as an important technology to detect the expression of programmed death ligand 1 (PD-L1) non-invasively and in real time. As a PD-L1 inhibitor, small peptide WL12 has shown great potential in serving as a targeting molecule to guide PD-L1 blockade therapy in clinic. In this study, WL12 was modified with HBED-CC to label (68)Ga in a modified procedure, and the biologic properties were evaluated in vitro and in vivo. (68)Ga-HBED-CC-WL12 showed good stability in saline and can specifically target PD-L1-positive cells U87MG and PANC02. In PANC02-bearing mice, (68)Ga-HBED-CC-WL12 showed fast permeation in subcutaneous tumors within 20 min (SUV(max) 0.37) and was of higher uptake in 90 min (SUV(max) 0.38). When compared with 18F-FDG, (68)Ga-FAPI-04, and (68)Ga-RGD, (68)Ga-HBED-CC-WL12 also demonstrated great image quality and advantages in evaluating immune microenvironment. This study modified the (68)Ga-labeling procedure of WL12 and obtained better biologic properties and further manifested the clinical potential of (68)Ga-HBED-CC-WL12 for PET imaging and guiding for immunotherapy.